Liquefied petroleum gas fuel valve



July 10, 1956 E. E. RUSH 2,753,856

LIQUEFIED PETROLEUM GAS FUEL VALVE Filed D80. 7. 1951 2 Sheets-Sheet 1 24 VAPORIZER LL ll INVENTOR. E.E. RUSH L.P. GAS FUEL TANK A T TORNEVS BY M July 10, 1956 E. E. RUSH 2,753,856

LIQUEFIEQ PETROLEUM GAS FUEL VALVE Filed Dec. 7, 1951 2 Sheets-Sheet 2 R m v m 1 F r i i 5 g 5;

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E.E. RUSH A TTORNEVS ORIFICE United States Patent LIQUEFIED PETROLEUM GAS FUEL VALVE Elton E. Rush, Bartlesville, ()lrlm, ass'ignor to Phillips Petroleum Company, a corporation of Delaware Application December 7, 1951, Serial No. 260,368

12 Claims. (Cl. 123-120) This invention relates to internal combustion engine operation. In one aspect it relates to apparatus for the use of liquefied petroleum gas as fuel for internal combustion engines. In another aspect it relates to safety apparatus for the use of liquefied propane as an internal engine fuel.

An object of this invention is to devise an apparatus for use with liquefied propane as an internal combustion engine fuel. Another object of this invention is to devise an apparatus for use in controlling pressures in fuel tanks in which liquefied propane is stored as internal combustion engine fuel. Still other objects and advantages of my invention will be realized uon reading the following disclosure.

Since the vapor pressure of commercial propane under atmospheric temperature conditions is quite high, that is, of the order of 200 pounds per square inch at 100 F., the use of heavy pressure tanks as fuel tanks is necessary. At temperatures higher than 100 F. for example, during the summer season, fuel tank pressures exceed 200 p. s. i.

Current commercial propane specifications permit a maximum tank pressure of 225 p. s. i. at 105 F. Tanks now in frequent use are built for 200 p. s. i. working pressure and are fitted with relief valves set to relieve pressures above 250 pounds. In public transportation service relief of fuel vapors to the atmosphere creates a hazard and the safe utilization of liquefied fuel stored under such pressures becomes a problem requiring careful consideratlon.

According to my invention I have devised an apparatus which permits removal of vaporous propane from the vapor containing section of the fuel tank. Removing vaporous propane permits evaporation of liquid propane with the resultant cooling of the tank contents. As the liquefied propane becomes cooled through evaporation its vapor pressure decreases. When the liquid propane becomes cooled to a considerable extent, further cooling may be to such a degree that evaporation is retarded below a rate at which propane gas is needed for operation of an engine. In my apparatus I make provision for utilizing propane gas as long as it is available under 'sufiicient pressures and if propane is needed at a faster rate, liquid propane is withdrawn from the tank to supplement the vapor for carburetion purposes.

In the drawing, Figure 1 is an elevational view, in diagrammatic form, of a motor vehicle chassis provided with apparatus embodying the present invention. Figure 2 is an enlarged elevational view, partly in section, of a portion of the apparatus shown in Figure 1. Figure 3 is an elevational view, with parts broken away to show details of construction of a second type of valve which can be substituted for corresponding parts in Figure 1. Figures 4 and 5 are elevational diagrammatic views of a third and fourth fuel tank and valve assembly which can be substituted for corresponding parts in Figure 1. Figure 6 is an elevational view, partly in section, of a fuel tank and a fifth type of valve embodying the invention 2,753,856 Patented July 10, 1956 which can be substituted for corresponding parts in the assembly shown in Figure 1.

Referring now to the drawing and specifically to Figure 1, in which is illustrated diagrammatically a chassis 11 of a motor vehicle equipped with the apparatus of my invention. Mounted on this chassis is an internal combustion engine 12 which is provided with a cooling system 13, an intake manifold 14 and a carburetor 15. On the rear end of the chassis is a fuel tank 16 of heavy gauge metal adapted for storage of liquefied propane. This tank is provided with a relief valve 25 which opens in case pressure relief becomes necessary. This tank is also provided with a valve 18, a portion of which extends into the tank. Directly above this valve is a motor controlled shut-01f valve 17 in the fuel line 19 for controlling communication of line 19 with tank 16 through valve 18. The conduit 19 for transmitting liquefied petroleum gas fuel leads from this valve 17 to a constant pressure outlet valve 20 and thence to another constant pressure outlet valve 21. The valve 21 is connected to the carburetor 15 by a conduit 26. The conduit 19 at a point between the valves 20 and 21 passes through a heat exchanger apparatus 22 which serves as a vaporizer to make certain that all propane is vaporous by the time it reaches the carburetor. This vaporizer 22 is supplied with heat from the cooling system 13 by way of a conduit 24 and the coolant is returned to the cooling system by way of a conduit 23. An oil pump 27 is shown for circulating oil through the lubricating system of the engine or if desired, this pump 27 may be a special oil pump used only for supplying oil pressures through a conduit '28 to a valve assembly such as illustrated in Figure 6 in the drawing, and to be explained later.

Figure 2 is illustrative of a heavy gauge metal propane fuel tank for use in such system as illustrated in Figure 1. It is preferable that such tanks be substantially cylindrical in form since vessels of that shape are better adapted to storing fluid materials under high pressures. Such a tank 16 of Figure 2 is provided with the metering and dispensing valve of my invention. The tank 16 is provided with a collar 44 into which is threaded the actual metering and dispensing valve. This valve consists substantially of a cylindrical valve body 45 which may be threaded over a portion of its length for securing to the collar 44. This valve body 45 contains a conduit throughout its length. The upper and lower ends of the conduit are threaded to accommodate some tubes 50 and 46, respectively. The upper end of the conduit 46 is so finished as to provide a seat for a valve 47. The lower end of the tube 46 extends to a point near the bottom of the tank and this tube is for removal of liquid propane under certain conditions. The tube or conduit 50 in the upper end of the valve body 45 conducts propane to such a fuel valve as illustrated by valve 17 of Figure 1. The end of the tube 50 is intended to form a shoulder against which the compression spring 49 rests to bias the valve 47 into its normally closed position. One or more orifices 48 are provided through the valve body 45 at a point within the tank and above the seat of the valve 47. These orifices 48 are for removal of vaporous propane from the vapor space 43 within the tank for use as fuel as long as the pressure in the tank is suflicient to furnish sufficient flow of propane vapor to the engine. When there is not sufiicient flow of propane vapor through the orifices 48, which flow is promoted by a reduction in pressure above the valve 47 due to the reduced intake manifold pressure, a pressure drop exists between this space and the vapor space 43 within the tank. Reference numeral 42 refers to the liquid containing space within the tank. In selecting the compression spring 49 I prefer such a spring as will permit the valve 47 to open when there is about a two-pound per square inch pressure differential between the vapor space 43 within the tank and the space within the valve body .5 above the valve 47. When the valve 47 is raised by a reduction of pressure, liquid propane is drawn through the valve and flows through the conduit 56 toward the carburetor. Referring now to Figure 1, the liquid propane from the tank 16 would under the above mentioned conditions flow through valve 18, through valve 17 and through conduit 19, and valve 20, to the vaporizer 22 in which the propane will be vaporized and the vapor will pass on through the valve 21 and conduit 26 to the carburetor 15.

In Figure 3 is illustrated an orifice conduit 62 which serves the same purpose as one or more orifices 48 of Figure 2, which orifice is adjustable in cross sectional area. This conduit 62 is provided with a valve seat 66 disposed in such a manner that a needle 63 may be installed as illustrated and upon turning a valve handle 64 the area of the conduit 62 is adjusted. This needle valve is prevented from leaking propane by the packing and take-up assembly 65. This entire assembly as illustrated in Figure 3 is identified by reference numeral 61 and may be used in the apparatus of Figure 2 merely by substituting it for the valve body 45.

In Figure 4 is illustrated an embodiment of my invention in which an orifice for controlling the fiow of vaporous propane is a separate and distinct piece of apparatus from the valve which controls the flow of liquid propane. Referring to Figure 4, a propane fuel tank 71 is partly filled with liquid propane 72 above which is some vaporous propane 73 under the vapor pressure of propane at the existing temperature. A conduit 79 containing a valve 75 also contains an orifice 76. This orifice 76 is intended to be the equivalent of one or more orifices 48 of Figure 2. That is, orifice 76 is an orifice of constant diameter. Orifice 76 discharges into a conduit 80. A tube 74 extending from the bottom of the tank 71 passes through the wall and is provided with a shut-off valve 77. To this shut-off valve is attached a conduit 81 containing a check valve 78, which valve 78 may be similar in all details to the valve assembly illustrated in Figure 2 of the drawing, minus the orifices 48. This valve 78 discharges into a conduit 82 which is connected to the conduit 80. Liquid from conduit 82 and vapor from conduit 80 pass on through conduit 80 to such an internal combustion engine as illustrated in Figure 1.

In Figure is illustrated an embodiment of my invention similar in function to the embodiment of Figure 3.

' The embodiment of Figure 3 differs from the embodiment of Figure 2 in that the cross sectional area or merely the opening of the orifice is adjustable by means of a needle valve. Thus in Figure 5 a needle valve is used to adjust the flow of vaporous propane. In this figure reference numeral 91 identifies the propane fuel tank containing liquid propane 92 and some gaseous propane 93 under pressure according to the existing temperature. According to this embodiment this vaporous propane passes from the top of the vapor space 93 through a conduit 96 and through an adjustable needle valve 95 into a conduit 97 for passage on to an internal combustion engine such as illustrated in Figure 1. A tube 94 extends from the bottom of the liquid containing section 92 through the wall of the tank and connects with a conduit 98. To this conduit 98 is connected a liquid propane valve 99 which valve may be similar in all respects to the valve embodiment illustrated in Figure 3, with the exception that the needle valve adjustable orifice is a separate and distinct piece of apparatus from the valve 99. This valve 99 discharges liquid propane through a conduit 100 into the above mentioned conduit 97 for passage to the vaporizer and engine.

In the operation of this apparatus of my invention and referring to Figure 2 of the drawing, as long as the fuel requirement of the engine is not excessive vaporous propane flows through one or more orifices 48 for passage to the engine. This flow of propane of course is influenced by the power requirement of the engine and directly by the pressure in the intake manifold. As mentioned hereinbefore the spring 49 is so selected that the valve 47 is forced open when the pressure in the vicinity of the spring 49 is decreased a definite amount below the pressure in the vapor space 43 in the tank. The spring 49 may be a 2 pound spring, that is it may be a spring such as will permit the valve 47 to open when the pressure above the valve 47 is 2 pounds lower than the pressure in the vapor space 43.

The principle upon which the operation of the system is based is as follows: When the external fuel valve is opened and the engine placed in operation, fuel flows in vapor form through the orifices into the fuel line and thence to the engine. The volume of vapor, at standard conditions, which flows through the orifices is a function of differential pressure across the orifices, number and size of orifices, and pressure of the vapors in the tank. Inasmuch as the maximum differential pressure across the orifices is set by the check valve spring, and the number and size of the orifices is fixed, the flow of vapor through the orifices is then a direct function of vapor pressure; i. e., the higher the vapor pressure, the greater the volume of vapor at standard conditions which will flow through the orifices. Therefore, so long as the ambient temperature is such that fuel vapor pressure is relatively high, the quantity of fuel supplied through the orifices will supply the demand of the engine and there will be a relatively small pressure drop across the check valve; hence, the check valve will remain closed. Should the demand of the engine exceed the supply available in vapor form, as when tank pressure has been substantially reduced, the pressure drop across the check valve Will increase and at some predetermined pressure drop, depending on the strength of the spring, the check valve will open and liquid will flow through the fuel line, as Well as vapors.

Thus, vapors only are withdrawn from the fuel tank so long as the tank pressure is sufiicient to supply the fuel requirements as vapor, and liquid is automatically withdrawn when necessary to supplement the fuel requirements. In this manner the development of excessive tank pressures is effectively prevented and only very simple and inexpensive equipment is required.

In the design of the equipment to be used in this system, it is obviously necessary to take into consideration the characteristics of the fuel to be used, the strength of the check valve spring, the size and number of orifices provided, and the atmospheric temperature range to be encountered. Since the properties of LP gas are well known over a wide range of temperatures, it is possible to calculate the requirements of any given system with a good degree of accuracy.

Example 1.-With an ambient temperature of 20 F., a fuel tank 2 ft. 1. D. by 6 ft. long, a check valve spring requiring 2 p. s. i. to open, and a single in. diameter orifice, the maximum pressure reduction due to withdrawal of vapor through the orifice is about 5.4 p. s. i. The resulting tank pressure is about 20.0 p. s. i. a., or 5.3 p. s. i. g. at normal atmospheric pressure (14.7 p. s. i. a). This pressure is ample to provide fiow of fuel in the system.

Example 2.At the other extreme, at an ambient temperature of F., the vapor pressure of pure propane is 257.5 p. s. i. a. Assuming the same system as above, the pressure reduction due to vapor withdrawal by an engine developing about 4050 H. P. is about 56 p. s. i. Engines requiring still more fuel, are provided extra fuel by withdrawing liquid propane through the check valve and liquid line.

The two examples above show that (l) the system is operable even at very low ambient temperatures and (2) suflicient pressure reduction is provided by normal engine operation to prevent excessive tank pressures i. e., above 250 p. s. i. g.) even at very high ambient temperatures.

Figure 6 of the drawing illustrates apparatus used in controlling the flow of vaporous and liquid propane according to my invention in conjunction with a fuel opening and closing valve. However, for starting up an engine with the use of such a valve, I provide a novel apparatus for priming the engine for starting purposes. This apparatus of Figure 6 is illustrated as installed partially in the tank of such an automotive assembly. Reference numeral 101 refers to the tank walls to which a collar 102 is attached by welding, as by weld 103. The valve assembly is then threaded into such a collar 102. The lower portion of this valve assembly is similar in principle and in most detail to the embodiment of apparatus in Figure 2. A tube 106 extends to the bottom of the tank and is for removal of liquid propane. The upper end of this tube is threaded into the threaded end of a valve body 104. This valve body 104 is similar in function in part to the valve body 45 of Figure 2. One portion of the upper end of the tube 106 forms a valve seat 128 for accommodation of a valve head 129. This valve head 129 is biased into a closed position by a compression spring 198. One or more orifices 105 are provided through the walls of this valve body 104 for passage of vaporous propane and serve the same function as orifices 48 of Figure 2. Vaporous propane which passes through orifices 105 passes upward and leaves the valve body through a threaded opening 109 which threaded opening is provided for a conduit for passage of the propane fuel to the carburetor. On the bottom of the valve head 129 is the stem 197 for guiding the valve and maintaining it in a fixed position with respect to the valve seat 128. The compression spring 108 may be a 2 pound spring similar to that mentioned hereinbefore, so that when a 2 pound pressure differential exists across orifice 105 the spring 108 will permit the valve head 129 to open and allow liquid propane to pass the valve. Under this condition liquid propane will flow upward through the valve body and out through the opening 109 to the carburetor.

In the upper portion of the central conduit of this valve body is disposed a valve stem 117 at the lower end of which is placed a valve head 118. This valve head is provided with an Oring seal 127 for making certain a positive seal when the valve is intended to be in 'a closed position. A compression spring 119 is provided for lifting the valve stem 117 to maintain the valve .118 in a closed position at all times when the spring is not under compression from an extraneous source. An annular space 131 is provided surrounding the valve stem 117 to permit easy flow of propane through this valve body, or drilled ports, not shown, in member 120 may be used in place of or with said annular space 131 in my valve for flow of propane through the valve body when the valve head 11% is opened. A valve stem guide and a seat for the spring 119 are provided as one piece of apparatus 120. Mounted on the top of valve body 104 is a pressure diaphragm assembiy consisting of a central body member 110 and an upper body member 111. Between these body members 110 and 111 is mounted a pressure operative diaphragm 114. it is intended that this diaphragm 114 is to move downward when fluid pressure is exerted above the diaphragm through a conduit 28 of Figure 1 and thence through a conduit 134 threaded into a thread opening 113. The compression spring 119 mentioned hereinabove is intended not only to hold the valve 118 in a normally closed position, but also is intended to exert an upward pressure against a push pin 115 which in turn contacts the under side of the diaphragm 114 to raise the diaphragm. A vent 112. vents the space below the diaphragm to the atmosphere. An O-ring sealing assembly 116 is provided as shown to prevent leakage of propane under pressure in the direction of the diaphragm. Above the diaphragm and disposed along the axis of the upper .body member 111 is a bellows 121. To the upper end of 6 this bellows is attached a conduit 123. This bellows 121 is held in place by'a threaded member 122. On the other end of the conduit 123 is provided another bellows 124. This bellows 124 is encased in a housing 126 which is provided with a push button 125. It is intended that this bellows housing 126 be mounted on the dash board of a motor vehicle for easy access to the operator or it may be installed on the floor board within easy reach of the operators foot.

An O-ring seal 135 is provided between the top of the main valve body 104 and the central body member to prevent leakage of propane.

This valve assembly is a positive shut-off valve for shutting off all flow of propane when the motor is stopped and for permitting the flow of propane when it is desired to start the motor.

The flow of the vaporous propane through the orifices 105 and of liquid propane upon raising of the valve head 129 is exactly the same as explained hereinabove in relation to Figure 2.

When the engine is not operating it is advisable to provide a positive shut-off valve so that there can be no leakage of propane. The leakage of propane would of course create a hazard. This shut-olf valve apparatus functions in the following manner. The valve head 118 with its O-ring seal 127 is biased upward to a sealing position against the corresponding portion of the valve body 104. The compression spring 119 is sufiiciently strong to seal this valve 118 and to raise the diaphragm 114 into such a position as illustrated in the drawing.

When it is desired to start the engine, it is merely necessary for the operator to push the button 125, which pushing collapses at least to some extent the bellows 124 which collapsing causes fluid within the bellows to flow through the conduit 123 into the bellows 121 and to extend this latter bellows. The extension of the bellows 121 against the top of the diaphragm 114 pushes this diaphragm downward to push the pin downward to open the valve 118. When the valve 118 is opened vaporous propane fiows through the orifices 105, through the valve body and out the opening 109 to the carburetor. Thus upon pushing the push button fuel is admitted to the carburetor for engine starting purposes. Then the ignition switch may be turned on and the engine started. When the engine starts its lubricating oil pump, as for example pump 27 of Figure 1 pumps oil under pressure for lubrication of the engine. A by-pass oil pressure line 28 also shown in Figure 1 may be provided to supply oil under pressure to conduit 134 of Figure 6. Oil under pressure from conduit 134 then enters the space between the valve body 111 and the diaphragm 114 and causes the diaphragm to be pushed downward to open or to hold open the valve 118 as long as the engine is running.

At any time as it is desired to shut off the engine, the ignition is of course turned off and when the engine stops the oil pressure decreases and the compression spring 119 operates to raise the diaphragm 114 and to close the valve 118. When valve 118 is closed no propane whatever can leave the fuel tank.

Referring to Figure 1 reference numeral 17 is intended to refer to such a shut-off valve assembly as that for positively closing off or opening up the fuel tank to the flow of fuel, and attached to this valve assembly 17 is a conduit 132 which is intended to represent the conduit 123 of Figure 6 and the push button assembly 133 of Figure 1 represents the push button 125 of Figure 6.

While certain embodiments of the invention have described for illustrative purposes, the invention obviously is not limited thereto.

I claim:

1. A liquefied petroleum gas fuel dispensing apparatus for use with an internal combustion engine operating on said fuel, comprising, in combination, a fuel storage tank, a liquid and gas dispensing valve in the wall of said tank, said valve comprising a generally cylindrical valve body rigidly attached to said tank, at least a portion of said valve body being disposed within said tank, a first conduit through said valve body to provide communication between the interior and the exterior of said tank the axis of said conduit coinciding with the axis of said valve body, a tube threaded into the inner end of said valve body in communication with said conduit and extending to the bottom of the tank for removal of liquid, the threaded end portion of said tube forming a valve seat, a valve in communication With said seat, said valve being adapted to open in response to a predetermined pressure drop across said valve to regulate flow of liquid fuel from the tank, a compression spring biasing said valve in a closed position against said seat, and a second conduit through the side wall of said valve body in the tank providing communication from the vapor space within said tank to said first conduit within said valve body at a point downstream of said valve as regards direction of flow of liquid fuel.

2. The liquefied petroleum gas fuel dispensing apparatus of claim 1 wherein said second conduit through the wall of the valve body is a needle valve conduit having a needle valve assembly disposed therein, the needle valve stem of said assembly extending rotatably through said valve body in a direction parallel to the axis thereof and terminating as a hand wheel outside said fuel tank.

3. A liquefied petroleum gas fuel control apparatus for use with an internal combustion engine powered by said fuel comprising, in combination, a fuel storage tank, an elongated valve body of circular cross section, a conduit of circular cross section extending throughout the length of said valve body, the axis of said conduit coinciding with the axis of said valve body, said valve body being rigidly fixed to the wall of said tank in such a manner that at least a portion of the valve body is positioned inside the tank, a tube threaded to the end of the valve body inside said tank and extending to the bottom thereof for removal of liquid fuel, a valve in the threaded end of said tube to control the fiow of liquid from said tank, a spring biasing said valve in a closed position, an orifice in said valve body providing communication between the vapor space in said tank and the conduit in said body at a point downstream of said valve, a second valve in the valve body conduit disposed on the downstream side of said orifice for closing off all flow of fuel from said tank, a compression spring biasing said second valve in a closed position an opening in the Wall of said valve body at a point outside said tank for connection with the carburetor of said engine, a pressure operative diaphragm assembly disposed over and closing the outer and open end of said conduit in said valve body, a push pin linking the side of the diaphragm closest to said tank with the end of the stem of said second valve in such a manner that upon exertion of pressure on the side of said diaphragm farthest from said tank said second valve opens and a manually operable means to open said second valve comprising an extensible first bellows in operable contact with the side of said dia phragm farthest from said tank, a second conduit connected operably with said extensible first bellows, an extensible second bellows operatively connected with said second conduit, said first and second bellows and their connecting conduit being filled with a hydraulic liquid and means for introducing oil under pressure from said engine into a space in said pressure operative diaphragm assenicbly on the side of the diaphragm farthest from said tan 4. A liquefied petroleum gas fuel dispensing apparatus for use with an internal combustion engine operating on said fuel, comprising, in combination, a fuel tank, a liquid and gas dispensing valve in the wall of said tank, said valve comprising a valve body rigidly attached to said tank, at least a portion of said valve body being disposed within said tank, a conduit through said valve body providing communication from the interior to the exterior of said tank, a tube rigidly attached to the inner end of said valve body in said tank and extending to the bottom of the tank for removal of liquid, the attached end of said tube terminating in said conduit of said valve body as a valve seat, a valve in operative communication with said seat, said valve being adapted to control flow of liquid fuel from said tank, a compression spring biasing said valve in a closed position against said seat, and a conduit through the wall of said valve body within the tank providing communication from the vapor space within said tank to the conduit within said valve body at a point downstream of said valve.

5. A liquefied petroleum gas fuel control apparatus for use with an internal combustion engine operating on said fuel comprising, in combination, a fuel storage tank, a valve body attached gas-tight to the wall of said tank in such a manner that a portion extends within said tank and a portion remains on the exterior, a tube attached to the inner tank portion of said valve body and extending to the bottom of the tank for removal of liquid, a conduit in said valve body providing communication from said tube to the exterior of said tank, the upper end of said attached tube in said valve body serving as a valve seat, a valve in operative communication with said seat, a spring biasing said valve in a closed position, an orifice in said valve body within said tank and downstream 01 said valve providing communication between the vapor space in said tank and said conduit, a second valve in the valve body Within said tank and downstream of said orifice for closing off all flow of fuel from said tank, a compression spring biasing said second valve in a closed position, an opening in the portion of the valve body outside the tank for connection with the carburetor of said engine, a pressure operative diaphragm assembly disposed over and closing the outer and open end of said conduit in said valve body, a push pin linking the side of the diaphragm closest to said tank with the end of the Stem of said second valve in such a manner that upon exertion of pressure on the side of said diaphragm farthest from said tank said second valve opens, a manually operable means to exert pressure on the side of said diaphragm farthest from said tank, and means for introducing oil under pressure from said engine into a space in said pressure operative assembly on the side of the diaphragm farthest from said tank.

6. A liquefied gas dispensing system comprising in combination a liquid storage tank adapted to store said liquefied gas as a liquid in a lower liquid storage zone, and to store vapors of said liquid in an upper vapor storage zone, a first dispensing conduit having an inlet disposed in communication with the interior of said tank in said liquid storage zone, an outlet at a point exterior of said tank, and passing through and sealed to the tank wall intermediate said inlet and outlet, a check valve in said first conduit controlling liquid flow therein from said inlet and adapted to open under a predetermined superior differential pressure across said valve from said inlet to said outlet to pass liquid from said inlet to said outlet, means biasing said check valve to close and check said liquid flow when said differential pressure is below said predetermined value, and a second restricted vapor conduit disposed and connected with an inlet in communication with said vapor storage zone and an outlet in communication with said dispensing conduit at a point between said valve and said outlet of said first conduit.

7. A liquefied gas dispensing system comprising in combination a liquid storage tank adapted to store said liquefied gas as a liquid in a lower liquid storage zone, and to store vapors of said liquid in an upper vapor storage zone, a first dispensing conduit having an inlet disposed in communication with the interior of said tank in said liquid storage zone, an outlet at a point exterior of said tank, and passing through and sealed to the tank wall intermediate said inlet and outlet, a check valve in said first conduit controlling liquid flow therein from said inlet and adapted to open under a predetermined superior differential pressure across said valve from said inlet to said outlet to pass liquid from said inlet to said outlet, a spring biasing said check valve to close and check said liquid flow when said differeutial pressure is below said predetermined value, and a second restricted vapor conduit disposed and connected with an inlet in communication with said vapor storage zone and an outlet in communication with said dispensing conduit at a point adjacent to said valve and between said valve and said outlet of said first conduit.

8. A liquefied petroleum gas fuel dispensing apparatus for use with an internal combustion engine operating on said fuel comprising a body member adapted to be sealed to a fuel tank, a first conduit through said body member to provide communication from the interior of a tank to the exterior, a tube attached to said body member to provide communication from the liquid containing space of said tank to said conduit, a check valve in said conduit adapted to control flow of liquid from said tank, said valve being adapted to open in response to a predetermined pressure drop across said valve in the normal direction of flow of liquid therethrough, an opening through the wall of said body member on the downstream side of said valve with respect to the direction of flow of liquid, said opening being adapted to pass vapor from said vapor space of said tank to said conduit, a compression spring biasing said valve in a closed position, and said valve being adapted to open in response to a pressure drop across said valve greater than a predetermined pressure drop.

9. A liquefied petroleum gas fuel dispensing apparatus for use with an internal combustion engine operating on said fuel, comprising, in combination, a fuel storage tank, a first conduit leading from the vapor space of said tank to the carburetor of said engine, an orifice in said conduit, a second conduit leading from the liquid containing space of said tank to said first conduit on the carburetor side of said orifice, a check valve in said second conduit for opening and closing said second conduit to the flow of liquefied fuel, a spring biasing said check valve in a closed position and said check valve being adapted to open in response to a pressure drop across said check valve greater than a predetes'i'nined pressure drop.

10. The apparatus of claim 9 wherein said orifice is an orifice plate assembly.

11. The apparatus of claim 9 wherein said orifice is a needle valve.

12. A liquefied petroleum gas fuel dispensing device for use with an internal combustion engine operating on said fuel comprising a body member, a conduit through said body member to provide communication from the interior of a fuel tank to the exterior thereof, said body member being adapted for attachment of a tube adapted to extend into the liquid containing portion of said tank, a check valve in said conduit adapted to control flow of liquid therethrough, said valve being adapted to open in response to a predetermined pressure drop across said valve in the normal direction of flow of liquid therethrough, an opening through the wall of said body member on the downstream side of said valve with re spect to the direction of flow of liquid, said opening being adapted to provide passage from the vapor space of said tank to said conduit, a compression spring biasing said valve in a closed position, and said check valve being adapted to open in response to a pressure drop across the check valve agreater than a predetermined pressure drop.

References Cited in the file of this patent UNITED STATES PATENTS 1,264,390 Hamilton Apr. 30, 1918 1,871,076 Mott Aug. 9, 1932 2,252,261 Jones Aug. 12, 1941 2,365,423 MacSpOrran Dec. 19, 1944 2,451,151 Byram Oct. 12, 1948 2,482,778 Joerren Sept. 27, 1949 2,487,863 Garretson Nov. 15, 1949 2,632,430 MacSporran Mar. 24, 1953 

1. A LIQUEFIED PETROLEUM GAS FUEL DISPENSING APPARATUS FOR USE WITH AN INTERNAL COMBUSTION ENGINE OPERATING ON SAID FUEL, COMPRISING, IN COMBINATION, A FUEL STORAGE TANK, A LIQUID AND GAS DISPENSING VALVE IN THE WALL OF SAID TANK, SAID VALVE COMPRISING A GENERALLY CYLINDRICAL VALVE BODY RIGIDLY ATTACHED TO SAID TANK, AT LEAST A PORTION OF SAID VALVE BODY BEING DISPOSED WITHIN SAID TANK, A FIRST CONDUIT THROUGH SAID VALVE BODY TO PROVIDE COMMUNICATION BETWEEN THE INTERIOR AND THE EXTERIOR OF SAID TANK THE AXIS OF SAID CONDUIT COINCIDING WITH THE AXIS OF SAID VALVE BODY, A TUBE THREADED INTO THE INNER END OF SAID VALVE BODY IN COMMUNICATION WITH SAID CONDUIT AND EXTENDING TO THE BOTTOM OF THE TANK FOR REMOVAL OF LIQUID, THE THREADED END PORTION OF SAID TUBE FORMING A VALVE SEAT, A VALVE IN COMMUNICATION WITH SAID SEAT, SAID VALVE BEING ADAPTED TO OPEN IN RESPONSE TO A PREDETERMINED PRESSURE DROP ACROSS SAID VALVE TO REGULATE FLOW OF LIQUID FUEL FROM THE TANK, A COMPRESSION SPRING BIASING SAID VALVE IN A CLOSED POSITION AGAINST SAID SEAT, AND A SECOND CONDUIT THROUGH THE SIDE WALL OF SAID VALVE BODY IN THE TANK PROVIDING COMMUNICATION FROM THE VAPOR SPACE WITHIN SAID TANK TO SAID FIRST CONDUIT WITHIN SAID VALVE BODY AT A POINT DOWNSTREAM OF SAID VALVE AS REGARDS DIRECTION OF FLOW OF LIQUID FUEL. 